Sleep and Circadian Rhythm Flashcards
Describe what happens during wakefulness?
Excitatory neurons in the ARAS are released from sleep centres in Reticular Formation which stimulate excitatory pathways in the CNS and PNS. Positive feedback sustains wakefulness in individuals
What do EEG recordings show?
Electrical activity in the brain
What will an EEG show when a person is relaxed/awake?
High fequency, high amplitude waves (alpha waves)
What will an EEG show in an alert, awake state?
High frequency, low amplitude, asynchronous waves (B-Waves)
Why is amplitude low in an alert EEG?
Brain is doing lots of things so desynchonised waves cancel each other out = low amplitude, high frequency
What are theta waves?
Low frequency, varied amplitude, Common in children, times of emotional distress and during sleep
What are delta waves?
Low frequency, high amplitude. Occur in deep sleep
Describe stage 1 in the sleep cycle?
Slow wave, non-REM,S-Sleep. Light sleep, easily roused, theta waves
Describe stage 2 in the sleep cycle
Eye movements stop, EEG shows sleep spindles (rhythmic waves of roughly 12-14 Hz)
Describe stage 3 in the sleep cycle
Delta waves interspersed with short episodes of faster waves, spindle activity declines
Describe stage 4 in the sleep cycle
Exclusively delta waves. V difficult to rouse. Sleep talking and sleep talking may occur
Describe REM sleep
Rapid Eye Movements occur and dreams may occur.
What are the physiological characteristics of deep, slow wave sleep?
Deep sleep occurs in first hours of sleep, most restful sleep type. Associated with decreased vascular tone (BP), respiratory and basic metabolic rate
What are the physiological characteristics of REM sleep?
Dreams occur, eye muscles show bursts of rapid activity, all other skeletal muscles ihibited,HR/RR become irregular and brain metabolism increases
What occurs in sleep deprivation?
Impairment of cognitive function, physical performance. Sluggishness and irritability
What does sleep support?
Neuronal plasticity, learning and memory, cognition, clearance of waste products from CNS, Conservation of whole body energy and immune function
Describe insomnia
chronic inability to obtain necessary amount/quantity of sleep to maintain adequate daytime behaviour
Describe night terrors
Children thrash and scream or may sit/stand up with eyes open and are not properly awake. Child does not remember the episode on waking the following morning
Describe somnambulism
Occurs exclusively in non-REM sleep, mainly in stage 4 sleep
Describe narcolepsy
Patients enter directly into REM sleep with little warning. Dysfunctional orexin release from the hypothalamus
